Grate bars



J. H. cULLlNG 3,063,696

Nov. 13, 1962 GRATE BARS 2 Sheets-Sheet 1 Filed March 9, 1959 J. HCULLING Nov. 13, 1962 GRATE BARS 2 Shee'cs-Sheel'l 2 Filed March 9, 1959finite This invention relates to grate bars, and more particularly tograte bars which are subjected in use to extreme conditions oftemperature, corrosion, abrasion and physical impact.

Among the several objects of the invention may be noted the provision ofgrate bars which have improved mechanical and corrosion-resistantproperties, and which will resist breaking, cracking, warping, chemicalattack, and extreme temperature and wear conditions; the provision ofsuch grate bars which may be used in moving conveyor furnaces and whichwill withstand both the mechanical and impact stresses and the extremetemperature and corrosion conditions present in such furnaces; and theprovision of grate bars of the class described which areself-straightening and aligning, and self-cleaning, and which effect asubstantial economy of manufacture and replacement, and which areflexible in design as to materials of construction. Other objects andfeatures will be in part apparent and in part lpointed out lhereinafter.

The invention accordingly comprises the constructions hereinafterdescribed, the scope of the invention being indicated in the followingclaims.

In the accompanying drawings, in which several of various possibleembodiments are illustrated,

FIG. l is a top plan view of a pallet of an endless conveyor of asintering furnace or the like, carrying a plurality of grate bars of thepresent invention;

FIG. 2 is a cross section of line 2-2 of FIG, l;

FIG. 3 is a side elevation of one embodiment of the present invention;

FIG. 4 is a cross section on line 4 4 of FIG. 3;

FIGS. 5-9 are exploded perspective views of tive other adidtionalembodiments of this invention; and,

FIG. l is an assembled perspective view of the grate bar embodiment ofFIG. 8.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

Referring now more particularly to FIGS. l and 2, a pallet of asintering furnace conveyor is indicated generally at referencenumeral 1. A large number of these pallets are linked together to form acontinuous articulated moving conveyor adapted to transport finelydivided material, such as ores or other chemical material layerwise, oras a moving bed, through heating or reaction zones to effect a desiredchemical or physical change in the properties thereof. Such a sinteringfurnace is well known to those skilled in this art, a specific exampleof such apparatus being a Dwight-Lloyd type machine. A grille forsupporting this bed of material is provided by mounting a number ofgrate bars 3 side-by-side in the pallet. More specically, the palletincludes a rectangular open frame comprising two spaced-apart sidemembers connected rigidly together by two outer cross beams 7 and twoinner cross beams 9. The pallet is adapted for movement along continuousparallel tracks by means of four anged wheels 1i journalled on shafts13, which are affixed to and project outwardly from the outer surfacesof pallet side frame members S.

Grate bars 3 are conveniently mounted within the pallet by lowering themindividually with a twisting motion so that their lower portions whichconstitute hooked foot members 15 lock under lips i7 of the crossmembers 9. This prevents the grate bars from moving in a verti-y dtatesPatent O l g '3,063,696 Patented Nov. 13, 1962 cal plane and falling outwhen the pallet traverses the ends and under reach of the conveyor atwhich times it is either tilted or upside down. A sufficient number ofgrate vbars 3 are assembled side-by-side to form a grille substantiallyacross the width of the pallet. In order to prevent sidewise movement ofthe bars in the pallet, two identical end bar units 19 are provided asller blocks. These end bar units do not include any foot members butrest on the upper surfaces of cross bars 7 and 9. One outer side of eachof the end bars 19 has a horizontal flange 21 which is engaged by thehead of retaining pin 23. The Shanks of these pins Z3 project throughholes in the pallet sides 5 and are provided with a cotterkey to preventtheir becoming disengaged from the pallet.

During operation of the sintering furnace, finely dif vided raw materialto b e heated and/ or chemically reacted is dropped as a layer on themoving pallet grille and heated by flames impinging .on the uppersurface of the moving bed and/or passing heated air through the grilleand the bed, Inasmuch as the upper surfaces of the grate are covered bythe material, they are subjected to extreme temperature, abrasion andcorrosion conditions which constitute a serious problem as to warping of the bars 3 and a .corroding and abrading away thereof. Moreover,because of the mecahnical stresses on the grate bars and the repeatedphysical impacts as the pallet moves from the upper reach .of theconveyor to the lower reach, these grate bars tend to break and crack.It is difficult to provide a single material or composition that iscorrosion, abrasion, and heat resistant and still able to withstand thephysical impacts and mechanical stresses to which these moving gratebars are subjected. Thus material which is sufficiently malleable orductile to possess the necessary impact strength usually has poor heat,abrasion, and corrosion resistance properties, and vice versa.

In accordance with the present invention, grate bars are-provided whichcan be subjected to and which will withstand these .extreme conditionsof temperature, corrosion, abrasion, impact and mechanical stresses.Moreover, my grate bars are self-straightening and aligning, as

` well as self-cleaning, and are economical to manufacture and replace.One embodiment of a grate bar of the present invention is showngenerally at 3A in FIGS. 3 and 4 to include an elongate rail or basecomponent 25 having an upstanding longitudinal rib 27 extending alongthe top edge substantially the entire length of and integral with thegrate base or body 25. Extending from but integral with the base 25 is afoot member 29 constituted by two hooks or lugs adapted to engage thepallet frame of a sintering machine conveyor or the like. Grate 3A alsoincludes an elongate channel-shaped cover 31 slidably and looselyengaging rib 27. Means are provided by downwardly depending integralears 33 and a pin 3S for locking ocver 31 to base 25. This preventsseparation of cover 3i and base 25 but permits relative longitudinalmovement and thermal expansion of cover 31. In order to assure a slightspacing and form slots between sides of adjacent bars 3A when assembledin the pallet, a number of integral abutments 34 are provided. Also tominimize mutual areas of contact between cover 31 and base 25 it will benoted that the cross section of rib 2'7 is of somewhat different shapethan the cross section of the generally C-shaped channel of cover 31.This decreases the thermal transfer or exchange of heat between thesetwo components of grate bar 3A.

Preferably the shield or cover 31 is made of a different material thanthat of base 25. A metallic, or nonmetallic, corrosion, abrasion, Vandheat resistant material which may be relatively brittle is used for thecover 31 while an impact resistant, malleable or ductile `metal ormetallic alloy is employed in the material of construction for base 25.For example, I may use a high-silicon cast iron (such as the Silaltype), an aluminum cast iron (such as a Tschugal type), other ferrousalloys of aluminum, silicon and chromium, or nonferrous alloys. Also,materials such as Monet, Hastelloy and Inconel, too expensive to use forthe entire grate bar, may be advantageously-used for cover 31. Materialsof low coeicients of thermal conductivity and expansion to resisttransfer of heat and warpage may be advantageously used for cover 31.For the base or body 25, plain carbon or mild steel, ductile iron,spheroidal or nodular graphite cast iron, high strength grey iron (suchas acicular ferritic iron, malleable cast iron, copper and aluminumalloys, etc.) are all impact resistant (although adversely aiected byhigh temperatures, abrasion and corrosion) and thus could advantageouslybe utilized.

`In some instances it may be desirable to further increase the thermalisolation or minimize the heat transfer between the cover and basecomponents of the grate bar, and for this purpose a coating or layer ofan insulating material on the interior surface of the channel of cover31 may be provided as indicated at 36. Such coatings, which may be anyrefractory material such as a ceramic or cermet material, additionallydecreases heat exchange beyond the decrease affected by the loose tit(e.g., 1/16 average spacing between the surface of the rib and theinterior channel surface). An exterior insulating, or corrosion, orabrasion resistant coating may also be applied to the exterior surfaceof the base 2S, particularly to rib 27, as indicated at 37, or to theexterior surface of cover 31, as indicated at 38.

In the operation of this device the separate cover and base portions andtheir loose interlocking provides important advantages. For example, thetemperature of the base is maintained at a low level relative to thehighly heated, abraded and corrosion-exposed cover 31. The limitedrelative longitudinal movement of the cover and base permits thermalexpansion without tendency to warping and misalignment, While stilllocking the two components of grate bar 3A together.

Another novel feature of the grate bars of this invention is illustratedin FIG. 5 in which a grate bar 3B is shown to comprise a body or base 39including symmetrical left and right hand rail or base sections 39L and39K of approximately equal length positioned in an end-to-endrelationship. In addition to longitudinal upstanding rib portions 41Land 41K which rib portions are on the upper edges of sections 39L and39R and separated therefrom by a groove, the sections 39L and 39R areprovided with thickened integral longitudinal reinforcing flanges 47 and49 along their lower edges. The coaxial ribs 41L and 41R are distinctlyrounded at their top surfaces so as to minimize areas of contact withthe channel of a grate bar cover 51. This cover is provided with a tabS3 at each of its outer ends. Upon sliding cover 51 onto base sections391. and 39R, it is loosely locked in place by bending tabs 53 downwardso as to provide limited relative longitudinal motion between the baseand cover components of bar 3B. This grate bar generally has the variousoperational and structural advantages of grate bar 3A, but in additionprovides an economy of replacement in that upon damage to base member 39replacement of only one part thereofmay be accomplished.

The FIG. 6 grate bar, indicated at 3C, differs from bar 3B in that aone-piece base member 57 is employed and the locking means areconstituted by ears 55 at each of the outer ends of base component 57.Also, a multiple-piece cover component comprising a left section S9L, amidsection 59M and a right section SSR are employed. These coversections are slidably engaged in an end-to-end relationship onopstanding rib 61 of base 57. It will be noted that the loose lockingaction provided by bent-over tabs 55 provides a relative longitudinalmovement and the loose tit on rib 61 provides so'me lateral play,- Whichactions 4 make bar 3C substantially self-cleaning and self-aligning Whenused in the pallets 1. Moreover, the use of a multiple-piece coverfurther insures against warpage.

The FIG. 7 embodiment discloses a two-piece cover 63 comprising a leftsection 6.3L and a right section 63R of unequal lengths. The base memberof this grate bar includes a left rail or section 65L and a right railor section 65K. These base sections are of equal length and aresymmetrical. The locking means of this grate bar is constituted by theintegral yabutments or stops 67L and 67K formed at the outer ends ofbase sections 6SL and 651%. When these base sections are axiallyslidably engaged in the channel of cover 63 and the foot members of 6Land GSR are engaged between the pallet cross members 9, separation ofall components is prevented while rel-ative longitudinal movement andthermal expansion are permitted. The grate bar of this embodiment,indicated generally at 3D, functions in generally the same way as thepreceding grate bar embodiments and has the same general advantages, butin addition has a locking arrangement that is preferable in certain waysto those illustrated and described above.

Another embodiment, indicated generally at 3E (FIG. 8), comprises amodified base member 69 made up of a left rail or section 69L and aright rail or section 69R of equal length and symmetrical. In thisexemplary grate bar, the locking means comprise a pair of shoulders 71L`at the outer end of 69L and a similar pair of shoulders 71R at theouter end of base section 69K. Also, the cross section of ribs 72L and72R is ofgenerally triangular shape. Another additional feature of thisgrate bar 3E is its cover which includes three sections 73L, 73M and 73Rarranged axially end-to-end. The abutting ends of 73L, 73M and 73R aremade mutually overlapping by providing cut-away portions or notches 75and 77 at the outer upper ends of cover section 73M, and by providingthe inner ends of 73L and 73R with tongues 79 and 81 adapted to mate andoverlap therewith. Also, a number of laterally extending integralspacers 83 are provided along the upper 'surfaces of cover sections 73Land '73K for sidewise spacing of adjacent grate bars when assembled toform the grille of a movable pallet. When these components of grate bar3E are assembled as shown in FIG. l0, they are all held loosely lockedtogether by the engagement of the foot member inside the anges ofmembers 9 of pallet 1. This embodiment has the additional structuraladvantage of being able to replace any one, two or three sections of thegrate bar cover, or one or two sections of the grate bar base,separately depending on the relative Wear or damage thereto, and effectsa substantial economy in repair and maintenance. Parts stocking problemsand costs are further minimized because the two sections of the gratebar are identical and two of the three cover sections are the same.

A still further embodiment is illustrated in FIG. 9 in which grate bar3F includes a three-section cover indicated at SSL, 85M and SSR adaptedto be slidably engaged on the upstanding rib of a two-piece basecomprising a left rail or section S'L and a right rail or section 87K.It will be noted that locking means 891. and 89K of these grate barsections are similar to those shown at 67L and 67K in FIG. 7, but thatthe foot member differs somewhat. The foot member in this embodiment isconstituted by two eyes 91 and 93, which are adapted to be engaged by apallet which would have transverse rods instead of L-shaped crossmembers `9 as shown. It is to be understood that grate bars having footmembers of a variety of configurations other than those specicallyillustrated and described herein are within the scope of the presentinvention.

It will be understood that the interlocking relationship between thecover sections and hase sections of the various embodiments preventslateral separation of the cover sections and the base sections.

The cover and base components of the grate bars may be manufactured byany of a number of conventional processes. For example, they may be castby conventional sand-molding or permanent molding methods or by shellmolding, die casting, stamping, forging, or extrusion. The coatings,such ceramic, or a metal or metal alloy, which may be applied to theouter surfaces of the cover component for enhancing the corrosioninhibition features of the bar; interior coatings of the cover channel;and exterior coatings of the base member for diminishing the heattransfer from the cover to the base components, may be formed by any ofthe customary coating methods such as sprayings, anodizing, vapor-phasedeposition, fusion Welding or brazing, electroplating, sintering, etc.Also, it is to be understood that the grate bars of this invention areuseful not only in sintering furnaces, but in all types of apparatus inwhich grate bars are moved and subjected to high temperature andmechanical impact and abrasion and chemically corrosive conditions. Forexample, these grate bars would be useful in equipment used in manyindustrial processes such as in the roasting or sintering of ores offerrous and nonferrous materials, in the cement industry for coolerconveyors from calcining kilns, etc.

In View of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

I claim:

1. A grate bar comprising an elongate base having an upstanding ribextending substantially the entire length of said base and a foot memberextending from the edge of the base opposite said rib, said baseincluding a left and a right section positioned in an end-to-endrelationship, an elongate cover of channel shape slidably engaging saidrib, said cover comprising three sections positioned in end-to-endabutting relationship and covering said rib, said rib having an outersurface thereof which differs in configuration from that of the innersurface of the channel of said cover sections whereby areas of linealcontact between said cover sections and rib are minimized and heatexchange between said cover sections and base is decreased, and meansfor locking said cover sections to said base to prevent both substantialrelative longitudinal movement and lateral separation of said coversections and base while permitting thermal expansion of said coversections.

2. A grate bar as set forth in claim 1 in which the outer surfaceconfiguration of said rib is generally triangular and the inner surfaceconfiguration of said channel shaped cover is generally C-shaped.

3. A grate bar as set forth in claim l in which the outer two sectionsof the cover are identical and in which portions of the upper surfacesof said outer two cover sections and the interposed third section arerelatively overlapped so as to form one continuous substantially flatupper surface of said cover.

4. A grate bar as set forth in claim 1 in which the base and covercomprise diierent metallic materials, the base material being of a highimpact strength and the cover material being corrosion and heatresistant.

5. A grate bar comprising an elongate base and an elongate cover ofchannel shape for the base, said base comprising two rails arranged inend-to-end relation with adjacent ends of said two rails in contiguousrelation, each of said rails having at least one groove extendinglongitudinally thereof along one side, the portion of each rail abovethe groove constituting a rib, the grooves in said two rails beingaligned, said cover being of channel shape straddling said ribs inendwise slidable relation thereto and having a portion extending intosaid grooves slidably keying said cover and rails together, theconfiguration of the outer surface of said ribs being different fromthat of the inner surface of the channel-shaped cover whereby areas oflineal contact between the cover and ribs are minimized and heatexchange between said cover and ribs is decreased, and interengagingparts on said cover and rails adapted to hold said cover and railsagainst substantial endwise sliding movement relative to one another,each rail having a depending foot at its end adjacent the other rail,said interengaging parts including a stop at each of the outer ends ofsaid base rails, each stop comprising an abutment integral with saidrespective rails adapted to project laterally from said rails and toloosely engage a respective end of said channel-shaped cover.

6. In a furnace including a series of pallets linked together to form anarticulated moving endless conveyor, each of said pallets carrying aplurality of grate bars arranged side-by-side to form a substantiallyfiat grill adapted to support a layer of nely divided material; each ofsaid grate bars comprising an elongate base and an elongate cover forthe base, said base including two rails arranged in end-to-end relationwith adjacent ends of said two rails in contiguous relation, each ofsaid rails having a dependent foot at its end adjacent the other rail,said foot members engaging said pallet and securing said grate bar tosaid pallet, each of said rails having at least one groove extendinglongitudinally thereof along one side, the portion of each rail abovethe groove constituting a rib, the grooves in said two rails beingaligned, said cover being of channel shape straddling said ribs inendwise slidable relation thereto and having a portion extending intosaid grooves slidably keying said cover and rails together, theconfiguration of the outer surface of said ribs being different fromthat of the inner surface of the cover whereby areas of lineal contactbetween the cover and ribs are minimized and heat exchange between saidcover and ribs is decreased, and interengaging parts on said cover andrails adapted to hold said cover and rails against substantial endwisesliding movement relative to one another said interengaging partsincluding a stop at each of the outer ends of said base rails, each stopcomprising an abutment integral with said respective rails adapted toproject laterally from said rails and to loosely engage a respective endof said channel-shaped cover.

References Cited in the le of this patent UNITED STATES PATENTS 24,316Low lune 7, 1859 111,031 Batchelor Ian. 17, 1871 311,633 Austin Feb. 3,1885 663,365 Sergeant Dec. 4, 1900 1,476,337 Holt Dec. 4, 1923 1,913,010Street June 6, 1933 2,258,280 Decker Oct. 7, 1941 2,278,316 Hulson Mar.31, 1942 2,278,317 Hulson Mar. 3l, 1942 2,700,849 Klotzboch Feb. l, 19552,708,107 Holcroft et al May 10, 1955 2,835,485 Woody May 20, 1958FOREIGN PATENTS 347,461 Great Britain Apr. 30, 1931 753,570 GreatBritain Iuly 25, 1956

